Large artery stiffness predicts ischemic threshold in patients with coronary artery disease

Objectives The goal of this study was to determine whether large artery stiffness contributes to exercise-induced myocardial ischemia in patients with coronary artery disease (CAD). Background Large artery stiffness is an independent predictor of cardiovascular mortality and a major determinant of pulse pressure and, thus, cardiac afterload and coronary perfusion. Clinical relevance of the hemodynamic consequences of large artery stiffening has not previously been demonstrated in relation to myocardial ischemia. Methods We hypothesized that stiffer large arteries would reduce myocardial ischemic threshold as assessed by time to ST-segment depression of 0.15 mV during a treadmill exercise test in patients with CAD. Ninety-six patients with CAD (78 men) age 62 ± 9 years (mean ± SD) were classified as having single (52 patients), double (31 patients), or triple (13 patients) coronary vessel disease, based on angiographically confirmed stenoses >50%. Systemic arterial compliance, distensibility index, aortic pulse wave velocity, and carotid augmentation index were measured using carotid applanation tonometry and Doppler velocimetry of the ascending aorta, at rest. Results In univariate analysis, all large artery stiffness/compliance indexes correlated with time to ischemia (p = 0.01 to 0.009). Both carotid (p = 0.007) and brachial (p = 0.001) pulse pressure also correlated inversely with time to ischemia. In multivariate analysis including other major risk factors plus severity of coronary stenosis, indexes of arterial stiffness were significant independent predictors of ischemic threshold. Conclusions Within a patient group with moderate CAD, large artery stiffness was a major determinant of myocardial ischemic threshold.